Diabetes is associated with several long-term complications. Amongst the most devastating is lower limb amputation. The most frequent cause of amputation is the diabetic foot ulcer. Ulcers occur in about 10-25% of patients with diabetes and can lead to lower limb loss in up to 80 % of cases.
WHAT IS A DIABETIC FOOT ULCER?
Any skin breakdown or ulceration should heal in a timely fashion in healthy individuals. Diabetics tend to develop foot deformities possibly due to metabolic nerve injury (neuropathy). This can lead to an imbalance between certain groups of muscles controlling foot and toe movement. As a result of this imbalance diabetics tend to develop specific foot deformities such as hammer and claw toes and collapse of plantar arch. Diabetics also might not have good sensation in their soles (Sensory Neuropathy) and therefore can not feel pain. Also, skin tends to get dry and easily cracks if not adequately moisturised. Any foreign body in a patient’s shoe can cause a superficial wound that might not be felt by the patient due to a loss of protective sensation and can lead to a deep ulcer and limb loss later on. Most of the time, however, patients develop callus in the areas with high pressure due to underlying bone and joint deformities. This callus is abnormally hard skin which can lead to disruption of underlying tissue and can become infected. An ulcer then develops and this can affect underlying bones and joints. If not treated this situation can lead to limb loss and even to deterioration of the patient’s life functions.
Diabetics also tend to develop Peripheral Arterial Disease (PAD) and the distribution of the blockage and narrowing in their arteries has a very unique distribution. Unfortunately, most of the time small arteries below the knee level are affected, which makes treatment rather difficult. Lack of oxygen in such situations leads to non-healing ulcers or gangrene and without adequate treatment causes limb loss.
HOW IS DIABETIC FOOT AND ULCERS DIAGNOSED?
The important first step is taking a history of long-standing diabetes. Diabetic patients are usually seen by their podiatrist and also by a diabetologist and family doctor on regular basis. Their feet need to be seen either by the patient themself or their relatives, if they have visual disturbances. Every superficial wound should be seen by the patient’s family doctor and treated adequately. If healing is slow and non-responding to usual re-dressing it is time to refer the patient to a specialist. With a known history of diabetes previous ulcerations, foot deformities or even previous minor (toe) amputations, such referral should be obviously rather urgent. Podiatrists also are very important ‘gate keepers’ and their referral to a family physician and then to a specialist are highly appreciated. Diagnosis is based on ultrasound assessment of blood supply, measurement of the oxygen level in the foot skin, angiography and assessment of degree of neuropathy. In close cooperation with orthotics and a podiatrist a footprint is taken and plantar pressures are assessed. Foot X-ray and magnetic resonance imaging, or nuclear scan, might be necessary to diagnose deep tissue infection or osteomyelitis (bone infection).
HOW ARE DIABETIC FOOT ULCERS TREATED?
It is important to distinguish between different causes of diabetic foot ulcerations and then the treatment be tailored accordingly. For foot ulcers due to a lack of oxygen an adequate vascular or endovascular procedure is needed to improve the chances of healing (please see also PAD). Special skills are needed for such situations as diabetic’s arteries that need to be reconstructed are very stiff, small and fragile. Microsurgical skills are required for advanced foot-salvage procedures including soft tissue resurfacing. A surgical bypass or even a combination of bypass and free tissue transferred from distant part of the body can resurface even large foot defects and salvage the leg.
Neuropathic ulcers take, on average, more then 30 weeks to heal and their recurrence rate is high. In some situations where healing wasn’t successful and/or recurrence is unacceptable for a patient, a special reconstructive surgical procedure is possible to resurface the ulcerated area and correct underlying skeletal deformity. For such situations the patient is seen by other members of a multidisciplinary team. This includes orthopedic surgeons with special skills, podiatrists, orthotics and vascular surgeons who specialise in diabetic foot disorders. Every patient is thoroughly examined, the limb is assessed and then all reasonable therapeutic alternatives are discussed with the patient. Treatment is possible in a vast majority of situations and the outcome can be reliable, satisfactory and can significantly improve the patient’s quality of life. Postoperative preventive measures are crucial and can prevent development of further ulcers.